Three-dimensional net-like structure, and method and device for producing three dimensional net-like structure

ABSTRACT

A method of and an apparatus for manufacturing a three-dimensional netted structure which is capable of rendering it unnecessary to carry out a finishing operation in a later stage, improving the degree of straightness of the side surfaces of the netted structure, meeting a demand for finishing the netted structure to modified shapes, and improving the durability of the netted structure. A three-dimensional netted structure ( 1 ) using thermoplastic resin as a raw material or a main raw material is characterized by a three-dimensional plate type netted structure, in which a plurality of filaments are helically and randomly entangled and partly and thermally bonded together. The density of any of at least three surfaces or four surfaces on the outer periphery of the three-dimensional netted structure is preferably relatively higher than the density of the other portion excluding these surfaces, and flaked or chipped PET bottles are used as a raw material or a main raw material for thermoplastic resin, such PET bottles being directly crushed and then melted to provide flakes, suiting to recycling promoting age, working well in waste disposal cost reduction, the uses of the three-dimensional netted structure ( 1 ) including, chiefly, shock absorbing materials, cushioning materials, and sound-absorbing materials.

FIELD OF THE INVENTION

This invention relates to a three-dimensional netted structure used fora cushioning material and the like, and a method of and an apparatus formanufacturing the same.

BACKGROUND OF THE INVENTION

Known methods of manufacturing a void-carrying three-dimensional nettedstructure include a method disclosed in Japanese Patent PublicationKOKOKU No. S50-39185, or a method disclosed in Japanese Patent Laid-OpenKOKAI No. S60-11352, etc., which is adapted to manufacture resin cottonon which polyester fibers are bonded with a bonding agent made of, forexample, a rubber-based material. There are also methods of orapparatuses for manufacturing a void-carrying three-dimensional nettedstructure by entangling resin threads by endless belts, and such methodsor apparatuses include the invention disclosed in Japanese PatentLaid-Open KOKAI No. H11-241264, etc.

However, the demands for a product of such a three-dimensional nettedstructure have been diversified. It is necessary that each of nettedstructures manufactured be finished to one of different shapes bycutting or molding the netted structures to demanded shapes in a laterstage of the manufacturing stage. This causes a product finishingoperation to become very complicated.

A three-dimensional netted structure manufactured by a prior art methodbecomes low in density in some cases. Since both surface portions of abundle contact belt conveyors, outer surfaces of the bundle aresubstantially flattened. However, left and right end surfaces of thebundle have an irregular, helical shape, and side surfaces thereof havea laterally wavy non-straight shape.

The endless belts mentioned above by which a resin threads are entangledis liable to be damaged due to the heat, etc., so that there is a fearof encountering a problem concerning the durability of the endlessbelts.

Therefore, the present invention provides a method of and an apparatusfor manufacturing a three-dimensional netted structure, capable ofrendering it unnecessary to carry out a finishing operation in a laterstage, improving the degree of straightness of the side surfaces of thenetted structure, meeting a demand for finishing the netted structure tomodified shapes, and improving the durability of the netted structure.

SUMMARY OF THE INVENTION

In view of these various problems, the invention is a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments withwater so as to obtain a netted structure having sparse and denseportions arranged alternately in the material extruding direction. Thisenables the netted structure to be applied to a cushioning material andthe like which is made possible to be hung at a sparse portion thereofon a hook.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with a liquid so as to obtain anetted structure having hollow portions arranged in the materialextruding direction. This enables the hollow portions to be utilizedeffectively by inserting other members therein or by using the hollowportions in a different manner, and the netted structure to be therebyapplied to various uses.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with a liquid so as to obtain asheet having a percentage of void of substantially zero in the materialextruding direction. This enables the soundproofing and shock absorbingperformance of the sheet to be improved.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with a liquid so as to obtain anetted structure having not smaller than two separable regions. Thisenables the difficulty, which was encountered in a related art nettedstructure of this kind, in recycling a complex resin and the like to beovercome by providing the netted structure with not smaller than twoseparable regions.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with a liquid so as to obtain aninsulating material or a sound absorbing material. This enables thenetted structure to be used as a building material, an interiorfinishing material for automobiles, and materials for similar purposes.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;cooling the resultant filaments with a liquid; and applying afire-resistant material to the cooled filaments or enclosing the cooledfilaments with the same material or adding the same material to thecooled filaments. This enables the reliability of an interior heatinsulating material, an exterior heat insulating material, an interiorfinishing material for a side wall and an interior finishing materialfor automobiles to be improved.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, party and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with a liquid so as to obtain aseedbed for planting trees on a roof. This enables the recycling of theseedbed to be done, and the planting of trees on a roof to be promoted.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with a liquid so as to obtain agardening cushioning material. This enables the netted structure to beused instead of a wooden trellis, and the durability thereof to beimproved.

The invention is a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with a liquid so as to obtain anetted structure having polyhedral or miscellaneously shaped sidesurfaces.

The invention is a three-dimensional netted structure manufactured bypreparing a regenerated thermoplastic resin, especially, polyethyleneterephthalate as a raw material or a main raw material; forming theresin into a plurality of helically and randomly entangled, partly andthermally bonded filaments by extrusion molding; and cooling theresultant filaments with a liquid so as to obtain a recycled nettedstructure. This enables the recovery of polyethylene terephthalatebottles, etc. to be promoted.

The invention is a three-dimensional netted structure manufactured bypreparing a brittleness-causing raw material-containing thermoplasticresin as a raw material or a main raw material; forming the resin into aplurality of helically and randomly entangled, partly and thermallybonded filaments by extrusion molding, and cooling the resultantfilaments with a liquid so as to obtain a netted structure capable ofbeing brittle fractured by applying an external force thereto. Thisenables a shock occurring due to the collision of a vehicle to break thetexture of the three-dimensional netted structure, so that damage to avehicle due to the collision thereof can be prevented.

The invention is an apparatus for manufacturing a three-dimensionalnetted structure which is obtained by extruding molten filaments of athermoplastic resin, a raw material or a main raw material downward froma die having a plurality of holes; having the filaments drop naturallybetween partly-submerged drawing-down units; when a three-dimensionalnetted structure is manufactured by drawing said filaments between saiddrawing-down units at a speed lower than a filament dropping speed, adistance between said drawing-down units being set smaller than a widthof an assembly of said extruded filaments, said drawing-down units beingarranged so that at least three or four surfaces of the assembly of saidfilaments contact said drawing-down units before or after saiddrawing-down units are submerged. This renders it unnecessary to carryout a finishing operation in a later stage, and enables the degree ofstraightness of the side surfaces of the netted structure to beheightened.

The invention is an apparatus for manufacturing a three-dimensionalnetted structure which is obtained by extruding molten filaments of athermoplastic resin, a raw material or a main raw material downward froma die having a plurality of holes; having the filaments drop naturallybetween partly-submerged rollers; and drawing said filaments between therollers at a speed lower than a filament dropping speed, a distancebetween said rollers being set smaller than a width of an assembly ofsaid extruded filaments, at least one surface of the assembly of saidfilaments contacting said rollers before or after said rollers aresubmerged. This enables the simplicity of the apparatus and the easinessof designing the apparatus to be attained.

The invention is an apparatus for manufacturing a three-dimensionalnetted structure which is obtained by extruding molten filaments of athermoplastic resin, a raw material or a main raw material downward froma die having a plurality of holes; having the filaments drop naturallybetween partly-submerged, slidable surface-carrying plate members adistance between which is set so as to decrease gradually in thedownward direction; and drawing said resultant filaments between theplate members at a speed lower than a filament dropping speed, adistance between lower portions of the plate members being set smallerthan a width of an assembly of said extruded filaments, at least onesurface of the assembly of the filaments contacting the plate membersbefore or after the plate members are submerged. This enables theminiaturization of the apparatus to be attained by reducing or omittingmovable parts.

The invention is an apparatus for manufacturing a three-dimensionalnetted structure which is obtained by extruding molten filaments of athermoplastic resin, a raw material or a main raw material downward froma die having a plurality of holes; having the filaments drop naturallybetween partly submerged drawing-down units; and drawing said filamentsbetween said drawing-down units at a speed lower than a filamentdropping speed, a distance between said drawing-down units being setsmaller than a width of an assembly of said extruded filaments, at leastone surface of the assembly of said filaments contacting thedrawing-down units before or after said drawing-down units aresubmerged, a cross section of outer circumferential members of thedrawing-down units being set to modified shapes. This enables anoperation in a later stage to be omitted.

The invention is an apparatus for manufacturing a three-dimensionalnetted structure which is obtained by extruding molten filaments of athermoplastic resin, a raw material or a main raw material downward froma die having a plurality of holes; having the filaments drop naturallybetween partly-submerged drawing-down units; and drawing said filamentsbetween said drawing-down units at a speed lower than a filamentdropping speed, a distance between said drawing-down units being setsmaller than a width of an assembly of said extruded filaments, at leastone surface of the assembly of said filaments contacting saiddrawing-down units before or after said drawing-down units aresubmerged, said die being provided with a complex die which has notsmaller than two chambers and a plural-hole-carrying mouthpiece, themolten filaments of a thermoplastic resin, a raw material or a main rawmaterial being extruded downward from the holes of said mouthpiece viadifferent passages isolated from one another by partitions. This enablesa separable three-dimensional netted structure to be manufactured.

The invention is an apparatus for manufacturing a three-dimensionalnetted structure which is obtained by extruding molten filaments of athermoplastic resin, a raw material or a main raw material downward froma die having a plurality of holes; having the filaments drop naturallybetween partly-submerged drawing-down units; and drawing said resultantfilaments between said drawing-down units at a speed lower than afilament dropping speed, a distance between said drawing-down unitsbeing set smaller than a width of an assembly of said extrudedfilaments, at least one surface of the assembly of the filamentscontacting the drawing-down units before or after the drawing-down unitsare submerged, the drawing-down units being provided withcircumferentially moving members, which are provided at circumferencesthereof with circumferentially extending metal nets or plate members.This enables the durability of the drawing-down units to be improved.

The invention is an apparatus for manufacturing a three-dimensionalnetted structure which is obtained by extruding molten filaments of athermoplastic resin, a raw material or a main raw material downward froma die having a plurality of holes; having the filaments drop naturallybetween partly-submerged drawing-down units; and drawing said filamentsbetween said drawing-down units at a speed lower than a filamentdropping speed, a distance between said drawing-down units being setsmaller than a width of an assembly of said extruded filaments, at leastone surface of the assembly of the filaments contacting saiddrawing-down units before or after said drawing-down units aresubmerged, regions of a high density of holes and regions of a lowdensity of holes being formed on a mouthpiece of said die. This enablesthe range of designing of the apparatus to be widened.

The invention is a method of manufacturing a three-dimensional nettedstructure, the method being applied to the inventions described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a three-dimensional netted structure ofa first mode of embodiment of the present invention;

FIG. 2A is a longitudinal sectional view of the three-dimensional nettedstructure of the first mode of embodiment of the present invention;

FIG. 2B is a longitudinal sectional view of a three-dimensional nettedstructure of a second mode of embodiment of the present invention;

FIG. 2C is a longitudinal sectional view of a three-dimensional nettedstructure of a fourth mode of embodiment of the present invention;

FIG. 2D is a longitudinal sectional view of a three-dimensional nettedstructure of a fifth mode of embodiment of the present invention;

FIG. 2E is a longitudinal sectional view of a three-dimensional nettedstructure of a sixth mode of embodiment of the present invention;

FIG. 2F is a longitudinal sectional view of a three-dimensional nettedstructure of a seventh mode of embodiment of the present invention;

FIG. 2G is a longitudinal sectional view of a three-dimensional nettedstructure of an eighth mode of embodiment of the present invention;

FIG. 3A is a longitudinal sectional view of the three-dimensional nettedstructure of a ninth mode of embodiment of the present invention;

FIG. 3B is a side view of the three-dimensional netted structure of theninth mode of embodiment of the present invention;

FIGS. 4A to 4G are sectional views of a three-dimensional nettedstructure of a third mode of embodiment of the present invention;

FIG. 5 is a perspective view of an apparatus for manufacturing thethree-dimensional netted structure of the first mode of embodiment;

FIG. 6 is an explanatory drawing showing the condition of an operationof the apparatus for manufacturing the three-dimensional nettedstructure of the first mode of embodiment;

FIGS. 7A and 7B are a side view and a front view of endless conveyors inthe same apparatus for manufacturing the three-dimensional nettedstructure;

FIGS. 8A to 8F are side views of modified modes of endless conveyors inthe same apparatus for manufacturing the three-dimensional nettedstructure;

FIG. 9A is a plan view of endless conveyors for an apparatus formanufacturing a four-surface-molded three-dimensional netted structure;

FIG. 9B is a side view of the same apparatus for manufacturing thethree-dimensional netted structure;

FIG. 9C is a side view of another mode of the apparatus formanufacturing a four-surface-molded three-dimensional netted structure;

FIG. 9D is a plan view showing the condition of a four-surface moldingoperation carried out by the same apparatus for manufacturing thethree-dimensional netted structure;

FIG. 9E is a plan view showing the condition of a three-surface moldingoperation carried out by the same apparatus for manufacturing thethree-dimensional netted structure;

FIG. 10A is a plan view of endless conveyors in an apparatus of anindependent driving system for manufacturing a four-surface-moldedthree-dimensional netted structure;

FIG. 10B shows endless conveyors provided with sliding plates at endsurfaces thereof in an apparatus for manufacturing a three-dimensionalnetted structure;

FIGS. 11A to 11H are plan views and a front view showing various modesof mouthpieces of a die;

FIGS. 12A and 12B are front views of modified modes of endlessconveyors, which are used for carrying out a four-surface moldingoperation, in an apparatus for manufacturing a three-dimensional nettedstructure;

FIG. 13A is a longitudinal sectional view of a three-dimensional nettedstructure of a tenth mode of embodiment;

FIG. 13B is a longitudinal sectional view of a three-dimensional nettedstructure of an eleventh mode of embodiment;

FIG. 13C is a longitudinal sectional view of a three-dimensional nettedstructure of a twelfth mode of embodiment;

FIG. 13D is a longitudinal sectional view of a three-dimensional nettedstructure of a thirteenth mode of embodiment;

FIG. 14A is a longitudinal sectional view of a three-dimensional nettedstructure of a fourteenth mode of embodiment;

FIG. 14B is a longitudinal sectional view of a three-dimensional nettedstructure of a fifteenth mode of embodiment;

FIG. 14C is a longitudinal sectional view of a three-dimensional nettedstructure of a sixteenth mode of embodiment;

FIG. 15 is a perspective view of the second mode of embodiment of theapparatus for manufacturing a three-dimensional netted structure;

FIG. 16A is a horizontal sectional view showing the portion of a mode ofembodiment of the apparatus for manufacturing a three-dimensional nettedstructure according to the present invention which is in the vicinity ofan upper part of a mouthpiece of a complex die;

FIG. 16B is a front view of a lower portion of the complex die;

FIGS. 17A and 17B are explanatory drawings of modified modes of thesecond mode of embodiment of the apparatus for manufacturing athree-dimensional netted structure;

FIGS. 18A, 18B and 18D are plan views showing various modes ofmouthpieces of dies;

FIG. 18C is a front view FIG. 18D;

FIGS. 19A to 19D are plan views showing various modes of the mouthpiecesof the dies;

FIG. 20 is an explanatory drawing showing the condition of an operationof the third mode of embodiment of the apparatus for manufacturing athree-dimensional netted structure.

FIGS. 21A and 21B are side views and front views of rolls in the sameapparatus for manufacturing a three-dimensional netted structure;

FIGS. 22A to 22G are side views of modified modes of rolls in the sameapparatus for manufacturing a three-dimensional netted structure;

FIG. 23A is a front view of the three-dimensional netted structure(applied to a gardening cushioning material and the like) of theseventeenth mode of embodiment;

FIG. 23B is a plan view of the same three-dimensional netted structure;

FIG. 23C is a side view of the same three-dimensional netted structure;

FIG. 23D shows a modified mode of the three-dimensional nettedstructure;

FIG. 24A is a plan view of a mouthpiece of a die in the fourth mode ofembodiment of the apparatus for manufacturing a three-dimensional nettedstructure;

FIG. 24B is a front view of the same;

FIG. 24C is a plan view of a mouthpiece of another die;

FIG. 24D is a front view of the same;

FIG. 25 is an explanatory drawing showing the condition of use of theseventeenth mode of embodiment of the three-dimensional nettedstructure;

FIG. 26 is an explanatory drawing showing the condition of another useof the seventeenth mode of embodiment of the three-dimensional nettedstructure; and

FIG. 27 is a construction diagram of a part of the fourth mode ofembodiment of the apparatus for manufacturing a three-dimensional nettedstructure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 2A, a three-dimensional netted structure 1 ofthe first mode of embodiment is a three-dimensional netted structure thecharacteristics of which reside in that the structure is athree-dimensional plate type netted structure formed out of aregenerated thermoplastic resin as a raw material or a main rawmaterial, in which a plurality of filaments are helically and randomlyentangled and partly and thermally bonded together and have two sidesurfaces, left and right end surfaces and upper and lower end surfaces.It is preferable that the density of surface-side portions of threesurfaces out of the side surfaces of this three-dimensional nettedstructure be relatively higher than that of the portion exclusive of thementioned surface-side portions. Namely, the three-dimensional nettedstructure 1 (refer to FIG. 2A) of the first mode of embodiment isthree-surface-molded. In this structure, regions thereof which extendinward from the opposite surfaces thereof by a predetermined distanceare molded to a high density, and the density of a region which extendsin a central inner portion of the netted structure is set lower than thementioned density. Thus, the remaining one surface of the structure hasa non-straight extending surface. Therefore, this netted structure hasan advantage in being not subjected to a process in a later stage. Inshort, a pair of surfaces of a large width and one side surface areforcibly molded by endless conveyors and the like which will bedescribed later, and the edges of these surfaces are formed morebeautifully than that of the other surface.

In this embodiment, flaked or chipped PET bottles are used as a rawmaterial or a main raw material of the regenerated thermoplastic resin.The raw material is obtained by pulverizing PET bottles as they are,melting the pulverized products, and forming the molten product intoflakes. This material is suited to the recycling promoting age. When thematerial is not a recycled product but a genuine product, themanufacturing cost per 1 m² of the netted structure increases double dueto the dry crystallization of or the removal of waste from the material.The material used in this embodiment can exercise its power in thereduction of the product scrapping cost. However, this embodiment canalso be applied to a thermoplastic resin and the like other thanregenerated materials of this kind. For example, polyolefines, such aspolyethylene, polypropylene, etc., polyesters, such as polyethyleneterephthalate, etc. polyamides, such as nylon 66, etc, polyvinylchloride, polystyrene, a copolymer and an elastomer obtained bycopolymerizing these resins as base materials, a material obtained byblending these resins, and some other similar materials. Thethree-dimensional netted structure, is used mainly as a cushioningmaterial, a shock absorbing material, a moisture absorbing material, asound absorbing material (to be provided under a floor material, in aninner portion of a structure and inside a wall), a heat insulatingmaterial (inner and outer heat insulating purposes), a wall surfacematerial, a roof gardening material, a concrete and mortar crackingpreventing material, interior finishing material for automobiles, andhas some other uses. This netted structure can also be applied to aninner portion of a double wall.

When a fire resistant material is mixed with the three-dimensionalnetted structure by holding the three-dimensional netted structurebetween nonwoven cloths or by attaching such cloths thereto, andapplying fire resistant paint to the netted structure, so as to givefire resistance to the three-dimensional netted structure, the resultantnetted structure becomes more preferable as a heat insulating buildingmaterial, a sound absorbing building material and the like.

This first mode of embodiment is molded so as to have a substantiallyuniform density at an inner portion thereof. The apparent density ofthis embodiment is preferably 0.02 to 0.9 g/cm³ (corresponding to apercentage of void of 36 to 98.4%), and specially preferably 0.05 to0.15 g/cm³. The three-dimensional netted structure 1 preferably has, forexample, a width of 0.1 m to 2 m and a thickness of 5 mm to 200 mm, andextends endlessly in the lengthwise direction. The netted structure iscut to a suitable length (for example, 90 mm) but the sizes of thenetted structure are not limited to the examples mentioned above.

A three-dimensional netted structure 2 (refer to FIG. 2B) of the secondmode of embodiment is four-surface-molded, and all the surfaces of thenetted structure extend straight. This netted structure is formed sothat the density of the regions thereof which correspond to those of thethree-dimensional netted structure 1 of the first mode of embodiment,and which extend inward from the left and right surfaces of the nettedstructure toward an inner portion thereof by a predetermined distance,becomes high, and so that the density of the region of the nettedstructure which is at a central inner portion thereof be set lower thanthe mentioned density. Namely, the regions of the netted structure whichextends from all the surfaces thereof except the upper and bottomsurfaces thereof to an inner portion of the netted structure by apredetermined distance are molded to a density higher than theabove-mentioned density.

A three-dimensional netted structure 3 of the third mode of embodimenthas a surface of modified shapes or a polyhedral surface. This type ofnetted structures include, for example, a netted structure 3A (refer toFIG. 4A) provided with a convex surface, a netted structure 3B (refer toFIG. 4B) provided with a concave surface, a netted structure 3C (referto FIG. 4C) provided with a plurality of continuously formed projectingand recessed portions, a netted structure 3D (refer to FIG. 4D) providedwith a plurality of saw-tooth-like portions, a netted structure 3E(refer to FIG. 4E) provided with a plurality of wavy portions, a nettedstructure 3F (refer to FIG. 4F) provided with rounded corner portions, anetted structure 3G (refer to FIG. 4G) provided with cut corner portionsof a predetermined angle (45°), or a suitable combination thereof, etc.In a job site of the execution of construction work, various modes ofnetted structures are demanded as products, and this embodiment can meeta demand for such netted structures. It is considered that formingnetted structures of complicated shapes causes various uses thereof tobe newly found. Especially, forcibly molding three or four surfaces ofthe three-dimensional netted structure as in the above-described firstand second modes of embodiment enables the various demands for theproducts to be met. Furthermore, in order to obtain netted structureshaving demanded miscellaneous surface shapes, netted structures aregenerally cut or molded so as to provide surfaces of modified shapesthereon on a later stage. According to this mode of embodiment, productscan be provided instantly without finishing the netted structure as tothe shape and sizes, which the products demand, on a later stage, sothat a later stage can be rendered unnecessary.

The three-dimensional netted structure 4 (refer to FIG. 2C) of thefourth mode of embodiment is provided with a single or a plurality (twoin this embodiment) of hollow portions 4A, 4B, and aims at furtherreducing the manufacturing cost.

The three-dimensional netted structure 5 (refer to FIG. 2D) of the fifthmode of embodiment has regenerated members 5C, 5D of the same ordifferent materials, such as plate type regenerated veneer members,plate type members of regenerated shredder dust and the like inserted inhollow portions 5A, 5B identical with the hollow portions 4A, 4B of thethree-dimensional netted structure of the fourth mode of embodiment.This embodiment aims at improving the sound absorbability, heatinsulating characteristics, cushioning characteristics and the like ofthe netted structure by using regenerated plate members.

In the three-dimensional netted structure 6 (refer to FIG. 2E) of thesixth mode of embodiment, the sound absorbing characteristics, heatinsulating characteristics, cushioning characteristics and impactresistance thereof are improved by increasing the density of parts ofthe inner portion of the same three-dimensional netted structure 1 as inthe first mode of embodiment in the direction of the thickness thereof,and thereby partly forming a single or a plurality (three in the sixthembodiment) of beam-like high-density regions 6A, 6B and 6C atpredetermined intervals.

In the three-dimensional netted structure 7 (refer to FIG. 2F) of theseventh mode of embodiment, the sound absorbing characteristics, heatinsulating characteristics, cushioning characteristics and impactresistance thereof are improved by increasing the density of parts ofthe inner portion thereof in the widthwise direction thereof, andthereby partly forming a plurality (one in this embodiment) of or asingle high-density region 7A.

In the three-dimensional netted structure 8 (refer to FIG. 2G) of theeighth mode of embodiment, the sound absorbing characteristics, heatinsulating characteristics, cushioning characteristics and impactresistance thereof are improved by forming a wavy high-density region 8Ain an inner portion of the same three-dimensional netted structure as inthe seventh mode of embodiment.

In the three-dimensional netted structure 9 (refer to FIG. 3A) of theninth mode of embodiment, the sound absorbing characteristics, heatinsulating characteristics, cushioning characteristics and impactresistance thereof are improved by forming a sheet 9A (non-void-carryingregion) in a predetermined widthwise extending inner portion of the samethree-dimensional netted structure as those 1, 2. Around the sheet 9A,filaments (resin threads) are entangled with one another. The sheet 9Amay be provided fully in the lateral direction as shown in the drawing,and also partly, for example, in the central portion and the like.

The sheet 9A in the three-dimensional netted structure 9 (refer to FIG.3B) of the ninth mode of embodiment is wave form in general and thesound absorbing characteristics, heat insulating characteristics,cushioning characteristics and impact resistance of the netted structureare improved. The reason why the sheet 9A can be molded in wave formresides in that a draw-down speed of rolls is lower than a resin threaddropping speed as will be described later. The intervals, height andwidth of the waves of the sheet 9A differ depending upon themanufacturing conditions, and are not limited to those shown in thedrawing. When the intervals of the waves of the sheet 9A are small, thewaves are bonded to one another in some cases. The ninth mode ofembodiment can be manufactured by using a slit (linear through hole) 75a shown in FIG. 11E.

Although illustrations are omitted, the present invention can also beapplied to three-dimensional netted structures of modified cross-sectionshapes, such as a triangular cross-section shape, a Y-type cross-sectionshape and the like.

(Apparatus for Manufacturing a Three-Dimensional Netted Structure)

An apparatus 10 for manufacturing a three-dimensional netted structurewill now be described.

This apparatus 10 for manufacturing a three-dimensional netted structureincludes as shown in FIG. 5. an extrusion molding machine 11, a pair ofendless conveyors 14, 15 (refer to FIG. 7) provided with endless members12, 13, a motor 16 adapted to drive the endless members 12, 13, atransmission 17 formed of a chain and a gear and adapted to change amoving speed of the endless members 12, 13, a water tank 18 adapted topartly submerge the two endless conveyors 14, 15 therein, a control unit19, and other meters, etc.

The endless members 12, 13 are formed by fixing with screws (not shown)a plurality of metal (stainless steel and the like in this embodiment)plate members 21 to a plurality (two for each conveyor) of endlesschains 12 a, 13 a (refer to FIGS. 7A and 7B) with a predetermined widthof clearance 22 (refer to FIG. 8A) left therebetween. Instead of theseplate members, a belt 23 of a stainless steel mesh (metal net) whichdoes not have the clearance 22 may also be used as shown in FIG. 8B.This mesh belt is formed by combining spiral wires with rods (powerribs), and various types of mesh belts are formed by varying the shapes,diameters and pitch of these two elements. Such mesh belts movesmoothly, keep the smooth belt surfaces horizontal excellently, standuse in hot temperature condition excellently, and are repaired simply.As shown by dotted lines in FIG. 7, stainless mesh belts 23 passedaround outer circumferences of the endless members 12, 13 can also beused in practice, and are preferably used when it is desirable toprevent the occurrence, which is ascribed to the presence of theclearance 22, of recessed and projecting portions on the mesh belt. Thecross section of the plate member 21 is rectangular, and variousmodified modes of plate members 21 are conceivable which include aconvex plate member 24 (refer to FIG. 8C), a concave plate member 25(refer to FIG. 8D), a saw-tooth plate member 26 (refer to FIG. 8E), acontinuously recessed and projecting plate member 27 (refer to FIG. 8F),etc.

As shown in FIG. 7, the endless conveyor 14 is provided with a drivingshaft 14 b having a sprocket 14 a around which the endless chain 12 aprovided vertically is passed, and a driven shaft 14 d having a sprocket14 c. The endless conveyor 15 is driven synchronously with the endlessconveyor 14, and provided with a driven shaft 15 b mounted with asprocket 15 a around which the endless chain 13 a is passed, and adriven shaft 15 d mounted with a sprocket 15 c.

As shown in FIG. 5, the extrusion molding machine 11 includes acontainer 31, a raw material feed port 32 provided on an upper portionof the container 31, a die 33, a mouthpiece 34 capable of being fixeddetachably to a lower end portion of the die 33. A range of thetemperature in an inner portion of the die of the extrusion moldingmachine 11 can be set to 100 to 400° C., and an extrusion rate of themachine 20 to 200 Kg/hr and the like. A range of the pressure in the dieis 0.2 to 25 MPa, which is equal to, for example, a discharge pressureof a 75 mm screw. When the thickness of the three-dimensional nettedstructure exceeds 100 mm, the equalization of the pressure in the die bya gear pump and the like is needed in some cases. Therefore, it becomesnecessary that the pressure in the die be increased by a gear pump andthe like so as to discharge filaments uniformly from the whole region ofthe interior of the die. To meet the requirement, the surfaces of theendless conveyors 14, 15 are formed so that these surfaces can be movedfreely so as to set the shape of a three-dimensional netted sheet. Thisenables a product having desired density and strength to be manufacturedin accordance with the shape (density or diameter of the holes H) of themouthpiece 34 of the die 33 and a transfer speed of the endlessconveyors 14, 15, and various demands for the products to be met.

An apparatus 50 for manufacturing a three-dimensional netted structurewhich is made of such a four-surface-molding machine as shown in FIGS.9A and 9B will now be described. This apparatus 50 for manufacturing athree-dimensional netted structure is provided with endless conveyors54, 55 having rotary shafts 54 a, 55 a which correspond to the endlessconveyors 14, 15 used in a two-surface-molding operation shown in FIG.7, and a pair of rolls 56, 57 disposed at lengthwise end portions of theendless conveyors 54, 55 and having rotary shafts 56 a, 57 a extendingat right angles to the shafts of the endless conveyors. The rotary shaft54 a is mounted with bevel gears 54 b, 54 c, while the rotary shafts 56a, 57 a are also mounted with bevel gears 56 b, 57 b. The bevel gears 54b, 54 c and the bevel gears 56 b, 57 b are meshed with each other, andthe rotary shafts 54 a, 55 a are driven synchronously by a motor M via achain C. Therefore, the rotary shafts 56 a, 57 a are also drivensynchronously. The other end portions of the rotary shafts 56 a, 57 aare supported on bearings 58 a, 58 b.

As shown in FIG. 9C, the apparatus may be an apparatus formed byarranging a pair of short endless conveyors 59 a, 59 b, the constructionof which is identical with the endless conveyors 54, 55, at right anglesto rotary shafts of rolls. In this case, the molding of a product can bedone more precisely, and the dimensional accuracy of a product isimproved.

As shown in FIG. 9D, the manufacturing of a three-dimensional nettedstructure can be done by using four-surface-molding techniques. Thethree-surface-molding of the product can also be done by using thementioned techniques as shown in FIG. 9E. Namely, when a certain type ofthree-dimensional netted structure is manufactured, two systems of diesare provided, and filaments are extruded in parallel. As a result, theproductive efficiency of the netted structure doubles.

As shown in FIG. 10A, an apparatus of a modified mode can be also usedwhich is formed by providing driving power sources (motors) instead ofthe previously-mentioned synchronous driving system so that endlessconveyors 64, 65 and rolls 66, 67 (endless conveyors also serve thepurpose) are driven independently of each other. Namely, in order tocarry out three-surface or four-surface-molding operation, endlessconveyors 64, 65 having rotary shafts 64 a, 65 a, and a pair of rolls66, 67 arranged at lengthwise end portions of these endless conveyors64, 65, and having rotary shafts 66 a, 67 a extending at right angles tothose of the endless conveyors are provided. The rotary shafts 66 a, 67a are also provided with respective motors M so that these rotary shaftsare driven independently of each other. The other end portions of therotary shafts 66 a, 67 a are supported on bearings 68 a, 68 b.

As shown in FIG. 10B, which shows another modified mode of theapparatus, in which a driving mechanism can be simplified by removingsuch two rolls 66, 67, two rotary shafts 66 a, 67 a, two bearings 68 a,68 b and two motors M as are provided in the preceding example, andproviding sliding curved plates 69 a, 69 b, the surfaces of which arecoated with polytetrafluoroethylene, in positions in which the rolls 66,67 were placed. These curved plates 69 a, 69 b are arcuate in sideelevation and positioned so that a distance between these curved platesdecreases gradually from upper portions thereof toward lower portionsthereof. The curved plates are formed to a rectangular shape in plan.

The holes of the mouthpiece 34 are downwardly made in series, from whichfilaments come out downward. The holes may be arranged at regularintervals or at non-regular intervals. The holes may employ staggered,orthogonal and various other types of configurations. When it is desiredthat the arrangement density of the holes be changed, a method ofpositively increasing the arrangement density thereof in end regionsonly is used in some cases. Changing the mode of the mouthpiecevariously enables various demands for the products to be met.Mouthpieces of a multiplicity of specifications can be used practicallywhich include, for example, a mouthpiece 71 (having holes H accountingfor 90% of the area of the mouthpiece 71)(refer to FIG. 11A) of 1.0m×180 mm in which about 3500 holes H of 0.5 mm in diameter are made, amouthpiece 72 (refer to FIG. 11B) in which the density of the holes H isset high only in a circumferential portion 72 a thereof, a mouthpiece 73(refer to FIG. 11C) in which the density of the holes H of frame-formingportion 73 b is increased so that the frame-forming portion constitutesseries-connected frames, a mouthpiece 74 (refer to FIG. 11D) in whichslits (linear through holes) 74 a to 74 c in addition to a multiplicityof holes H are formed so that the slits extend in parallel with shortersides of the mouthpiece, a mouthpiece 75 (refer to FIG. 11E) in which aslit (linear through hole) 75 a in addition to a multiplicity of holes His formed so that the slit extends in the lengthwise direction of themouthpiece, a mouthpiece 76 (refer to FIG. 11F) and the like in which aslit (linear through hole) 76 a in addition to a multiplicity of holes His formed so that the slit extends in a position near a lengthwise sideof the mouthpiece, and similar other mouthpieces, and a mouthpiece 77(refer to FIGS. 11G and 11H) and the like which have regions 77 c, 77 dnot provided with the holes H so as to make hollow portions therein, andwhich is provided under these regions with cross-section squareintroduction members (pipes, etc.) 77 a, 77 b projecting downwardtherefrom. The density of the holes H formed in these mouthpieces ispreferably 1 to 5/cm².

(Method of Manufacturing a Three-Dimensional Netted Structure)

This three-dimensional netted structure 1 is manufactured in thefollowing manner. First, flakes of regenerative PET bottles are heatedand dried for preventing the same from being hydrolyzed, and chemicalsfor excellently finishing the resultant product, or an antibacterialagent and the like are added suitably to the same product in some cases.When filaments come out flat from the mouthpiece 34 in the downwarddirection, the filaments are entangled helically owing to the entanglingactions of the endless members 12, 13 of the endless conveyors 14, 15.The filaments start being entangled at the portions thereof whichcontact the surfaces of the endless members 12, 13 at theentangling-starting time. The density of the portions of the filamentswhich are entangled is high, and that of the portions thereof which arenot entangled is low.

Next, as shown in FIG. 6, a three-dimensional netted structure 1, anobject netted structure is manufactured by extruding a moltenthermoplastic resin downward from a plurality of dies 33, having theextruded filaments of the resin drop naturally to a position between apair of partly submerged endless conveyors 14, 15, and drawing down thefilaments of the resin at a speed lower than the filament droppingspeed. When this netted structure 1 is thus manufactured, the twoendless conveyors 14, 15 are arranged so that a distance between theendless conveyors is set smaller than a width of an assembly of theextruded filaments of the molten resin, and so that both or one surfaceof the assembly of the filaments of the molten resin contacts theendless conveyors 14, 15 before or after these conveyors are submerged.

Both or one of the surface portion of the assembly of the moltenthermoplastic resin drops on the endless conveyors 14, 15, and moves toan inner side of the assembly, so that the surface portion of theassembly becomes dense. Therefore, the percentage of void of the surfaceportion becomes lower than that of a central portion which drops as itis into the water. It is a matter of course that the surface portion inwhich the percentage of void becomes low comes to have an increasednumber of nodes as compared with the central portion having a highpercentage of voids, and that the tensile strength of the surfaceportion becomes noticeably high. The surface portion having a lowpercentage of void comes to have a small area of voids, and forms animpact absorbing layer and a soundproofing layer.

A result showing that a percentage of void of the three-dimensionalnetted structure 1 as a whole high enough to have the netted structurefunction well is in the range of 50% to 98%, though these levels differwith the condition of execution of works on a job site was obtained. Inshort, it is considered that, when the density of the netted structureis high, sounds are blocked. A result showing that, in order to have thethree-dimensional netted structure function as a recycled soundabsorbing building material, a cushioning material, a heat insulatingmaterial and the like, the percentage of void thereof may be setpreferably to not lower than 70% was obtained. In short, when thepercentage of void is lower than 70%, the impact absorbing effect,soundproofing effect, heat insulating effect and cushioningcharacteristics of the netted structure are not in some cases soimproved as was expected. It is recommended that the three-dimensionalnetted structure 1 may be designed suitably with the percentage of voidset in the range of 70% to 98% in accordance with the use of the nettedstructure.

A sound absorbing material and a cushioning material have a preferablepercentage of void of 85 to 98%, an impact absorbing material to beprovided under a floor 40 to 80%, and a collision-preventing impactabsorbing material 60 to 90%. A preferable range of the percentage ofvoid varies with the use of the netted structure.

The percentage of void=100−{(B÷A)×100}, wherein A represents a productof the specific gravity of the resin and the volume of thethree-dimensional netted structure; and B represents the weight of thenetted structure.

The thermoplastic resin used in this method is obtained by pulverizingPET bottles into flakes, which are used as a raw material or a main rawmaterial. However, resins including a polymer, such as polypropylene,etc. or a resin obtained by blending a plurality of kinds of polymerstogether, etc. may be used as a main raw material without trouble aslong as the resin can be processed by a regular extrusion moldingmachine.

In the step of forming three-dimensional netted structures to finalmodified shapes, a mechanism for equalizing the inner pressure of thedies, and drawing down an assembly of filaments at two, three or foursurfaces thereof or at an intermediate portion thereof is used. Thisenables such characteristics to be given to this netted structuremanufacturing method that include its capability of attaining anapparent density of a product of 0.02 to 0.9 g/cm³, changing thefilaments of the molten resin from a randomly and helically entangledstate into a state of a flat plate, and turning the surface portions ofthe three-dimensional netted structure including the front, rear, leftend and right end surfaces with respect to the direction of thethickness thereof into flat surfaces and surfaces of modified shapes,i.e. projecting and recessed surfaces. The mouthpiece of a die used toform the three-dimensional netted structure is made so that a nettedstructure of a rod type shape, modified shapes (shape of a pipe and ashape of the letter “Y”), etc. and a netted structure of various othershapes devised by combining these shapes together can be obtained. Thethree-dimensional netted structure is subjected to compression by therolls of a draw-down machine to obtain a super-dense sheet structure.The inner pressure of the dies used to have the regenerated PET resindischarged uniformly from the dies is equalized, and the three or foursurfaces of an assembly of filaments of a molten resin extruded when thethree-dimensional netted structure is manufactured is brought intocontact with the draw-down conveyors by which these surfaces are shaped.In short, the assembly of filaments of the molten regenerated PET resinis formed at the three or four surfaces thereof to shapes of a finalproduct. For example, a resin filament assembly is drawn up as necessaryaround polygonal conveyors to form a product. In one of the methods ofobtaining a three-dimensional netted sheet, filaments of a molten resinare extruded downward from a plurality of dies, and dropped naturallyonto water surface or to a position between partly-submerged conveyors.Thus, a randomly and helically entangled filament assembly is made,which forms a three-dimensional netted sheet.

It was ascertained that, when the speed of the endless conveyors wasvaried, the density of a sheet of 1.0 m in width and 100 mm in thicknessvaried.

It was further ascertained that the density of the sheet varied inaccordance with the variation of a discharge rate of the extruder.

The mouthpiece 34 having about 3500 substantially regularly spaced holesH of 0.5 mm in diameter was fixed to the dies 33 having an area of 1.0m×180 mm in a uniaxial extruder having a screw of 75 mm in diameter. Thewater tank 18 having a water level in a position about 120 mm below thedies 33 is provided, and a pair of endless conveyors 14, 15 of 1.2 m inwidth were installed substantially vertically in the tank with aclearance of 50 mm left therebetween, in such a manner that upperportions of the endless conveyors project upward from the water level byaround 40 mm.

In this apparatus, the molten resin filament assembly was extruded fromthe mouthpiece 34 at an extrusion rate of 120 kg/hr to a positionbetween the endless conveyors 14, 15 so that two surfaces of the moltenresin filament assembly dropped on the endless conveyors, by controllingthe temperature of the dies 33 so that the temperature of the resinbecame 240° while plasticizing a regenerated PET resin by heating thesame. During this time, the draw-down speed of the endless conveyors 14,15 was set to 0.7 m/min. The molded product held between the endlessconveyors 14, 15 and moved down changed its direction in a lower portionof the interior of the water tank 18, and was moved from the side of thewater tank which is opposite to the extruder to the water surface. Whenthe molded product came out of the water tank 18, the water thereon wasblown off with compressed air or by a vacuum pump.

The three-dimensional netted structure thus obtained had a width of 1.0m, a thickness of 50 mm, and a density of 0.07 g/cm³ to 0.14 g/cm³. Thisnetted structure may be used as a heat insulating material, a groundmaterial, and a sound absorbing material, and for a drain pipe, etc.

The above-described three-dimensional netted structure 1 and apparatus10 for manufacturing the same netted structure enable a finishingoperation on a later stage to be omitted, the degree of straightness ofsurfaces of the netted structure to be improved, a demand for a nettedstructure having modified shapes to be met, and the durability of thenetted structure to be improved.

Owing to this mode of embodiment, the PET bottles which do not have usesin the existing circumstances newly find a use as materials for athree-dimensional netted structure, and it is considered that a recoverypercentage of the PET bottles will increase. This causes the recyclingof the PET bottles to be greatly promoted.

FIG. 12 shows a modified mode of the apparatus 50 for manufacturing afour-surface-molded three-dimensional netted structure, and FIG. 12A isa drawing corresponding to FIG. 9B and shows a pair of rolls 56, 57 asdescribed above which have a single or a plurality of projections 90 ato 90 c on the respective surfaces thereof (the illustrations of theroll 57 and its projections are omitted). These projections are formedso as to provide recesses in side surfaces of the three-dimensionalnetted structure. Each of the projections 90 a to 90 c has angularportions and an arcuate side portion in cross section. Although therecesses referred to above and formed in the side surfaces of the nettedstructure ought to become rectangular theoretically, the recesses becomecurvilinear since the resin filaments drop into the space between theendless conveyors from above as above-mentioned, to cause blind regionsin which the resin filaments do not enter to occur. In short, therecesses become roundish. FIG. 12B corresponds to FIG. 9C, and showsendless conveyors (the illustrations of the endless conveyor 55 and itsprojections are omitted) formed by providing a single or a plurality ofprojections 96 on the surfaces of two endless belt conveyors like thoseof the above-mentioned belt conveyors 54, 55, etc. This modifiedapparatus can also be formed by incorporating cams and springs in therotary bodies, such as the above-mentioned rolls 56, 57 or endlessconveyors 54, 55 so that the projections are forced out in the outwarddirection by the cams synchronously with the rotations of the rotarybodies. This enables the occurrence of blind regions to be reduced, andmore precise recesses to be formed. Since the construction of the otherparts is identical with that of the corresponding parts of the apparatusshown in FIGS. 9B and 9C, the illustrations and description of thelatter will be utilized and quoted.

A second mode of embodiment will now be described. The demands for therecycling of the products of the three-dimensional netted structureshave become diversified, and cannot be met under the presentcircumstances in some cases. For example, when it is desired that amixture of not smaller than two kinds of regenerated resins be utilized,some of these raw materials prove separable during recycling operationstherefor, and some non-separable. In a scene of labor for recycling rawmaterials, non-separable raw materials are sometimes mixed in a startingmaterial, and the recycling and utilizing of raw materials actuallybecome impossible in some cases in spite of the effort made to recyclethe materials. There are various cases where the same raw material isused for a certain purpose, which include a case where changing theshape of a product is desired, such as a case where forming sparse anddense regions is desired, a case where forming hollow portions on alater stage is desired and similar cases, or a case where improving themoldability of the materials is desired.

Therefore, this mode of embodiment is carried out so as to preventtroubles from occurring in the regeneration of a thermoplastic resin,and attain the easiness of changing the shape of a product.

A three-dimensional netted structure 101 of a tenth mode of embodimentis a plate type three-dimensional netted structure, the characteristicsof which reside in that the netted structure is formed by using aregenerated thermoplastic resin as a raw material or a main rawmaterial, and has a plurality of filaments helically and randomlyentangled and partly and thermally bonded together as shown in FIG. 13A.This netted structure is made of an inner region 101 a and an outerregion 101 b of the same or different raw materials. A boundary betweenthe inner region 101 a and outer region 101 b is shown by a solid line.The solid line is an imaginary line showing the boundary, and the sameapplies to the other modes of embodiment which will be described later.It is preferable that the densities of two, three or four surfaceportions of this three-dimensional netted structure may be relativelyhigher than that of the portion of the netted structure which isexclusive of these surface portions. Namely, the three-dimensionalnetted structure 101 (refer to FIG. 13A) of the tenth mode of embodimentis two-surface-molded. This netted structure is molded so that thedensity of regions thereof which extend from the opposite surfacesthereof toward an inner portion thereof by a predetermined distance ishigh. The density of an inner part of the central portion thereof is setlower than the mentioned density, and the other non-surface-moldedsurfaces are not straight-formed. Therefore, it becomes unnecessary thatthis netted structure may be processed on a later stage. In short, apair of surfaces of a large width and one side surface of the nettedstructure are forcibly molded by endless conveyors which will bedescribed later, and edges of these surfaces are set more beautifullythan those of the other surfaces.

A three-dimensional netted structure 102 (refer to FIG. 13B) of aneleventh mode of embodiment is a three-surface-molded netted structure,in which all the surfaces except the end surfaces and one side surfaceare set straight. The regions extending from all the surfaces of thenetted structure except the right side surface thereof toward an innerportion thereof by a predetermined distance are molded to a highdensity. This netted structure is made of an inner region 102 a and anouter region 102 b of the same or different raw materials.

A three-dimensional netted structure 103 (refer to FIG. 13C) of atwelfth mode of embodiment is four-surface-molded, in which all thesurfaces thereof except an end surface thereof are set straight. Thisnetted structure is formed by molding the regions, which extend from theleft and right side surfaces of the same netted structure as that of thefirst mode of embodiment to the inner part of the central portionthereof by a predetermined distance, to a high density with the densityof the region in the inner part of the central portion of the nettedstructure set lower than the mentioned density. Namely, the regionsextending from all the side surfaces of the netted structure toward theinner portion thereof by a predetermined distance are molded to a highdensity. This netted structure is made of an inner region 103 a and anouter region 103 b of the same or different raw materials.

A three-dimensional netted structure 104 (refer to FIG. 13D) of athirteenth mode of embodiment is a three-dimensional netted structureprovided with a single or a plurality of (one in this embodiment) hollowportions 104 c, and formed for the purpose of further reducing the costand for some other purposes. This netted structure is made of an innerregion 104 a and an outer region 104 b of the same or different rawmaterials.

A three-dimensional netted structure 105 (refer to FIG. 14A) of afourteenth mode of embodiment is formed of three layers of regions 105a, 105 b and 105 c of the same or different raw materials. The rawmaterials of all of the three layers of regions may be different. Theraw materials of the regions 105 a, 105 c may be identical, and that ofthe region 105 b may be different. The raw materials of the three layersof regions may be all identical. The netted structure is divided intothree layers of regions 105 a, 105 b and 105 c in the lengthwisedirection thereof.

A three-dimensional netted structure 106 (refer to FIG. 14B) of afifteenth mode of embodiment is made of two layers of regions 106 a, 106b of the same or different raw materials. The raw material of the twolayers of regions 106 a, 106 b may be different or identical. Thisnetted structure is divided into two layers of regions 106 a, 106 b inthe lateral direction thereof.

A three-dimensional netted structure 107 (refer to FIG. 14C) of asixteenth mode of embodiment is made of two layers of regions 107 a, 107b of the same or different raw materials. The raw materials of the twolayers of regions 107 a, 107 b may be different or identical. Thedirection in which this netted structure is divided into these regionsis that of the thickness of the netted structure unlike the direction inwhich the fourteenth and fifteenth modes of embodiment are divided.

In the embodiment shown in FIG. 3, a high-density sheet 9A (asubstantially non-void-carrying filled region) can be provided partly ina predetermined position in the lateral direction in the embodiment byforming the sheet and the other region by different extrusion moldingmachines through different paths. The description of this embodimentwill be quoted from that given previously with respect to the embodimentof FIG. 3.

Beside these netted structures, netted structures of modifiedcross-section shapes, such as a triangular shape, a shape of the letter“Y”, etc., the illustrations of which are omitted, can also be formed inpractice. As mentioned above, when a raw material is supplied to notsmaller than two regions provided on the mouthpiece, the regulation ofthe manufacturing conditions, such as the temperature of the rawmaterial, extrusion rate of the filaments, etc. can be made easily.

An apparatus 110 for manufacturing a three-dimensional netted structureof a second mode of embodiment will now be described.

This apparatus 110 for manufacturing a three-dimensional nettedstructure include as shown in FIG. 15 an extrusion molding machine 111,a pair of endless conveyors 114, 115 provided with endless members 112,113, a motor 116 for driving the endless members 112, 113, atransmission 117 formed of chains and gears and adapted to change themoving speed of the endless members 112, 113, a water tank 118 forsubmerging parts of the endless conveyors 114, 115 therein, a controlunit 119 and meters, etc.

The description of endless members 112, 113, etc. will be described byquoting that given previously with respect to the first mode ofembodiment.

As shown in FIG. 15, the extrusion molding machine 111 is formed ofcontainers 131 a, 131 b storing therein the same or different rawthermoplastic resin materials, raw material supply ports 132 a, 132 bprovided at upper portions respectively of the containers 131 a, 131 b,raw material supply pipes 133 a, 133 b connected to the containers 131a, 131 b respectively, a complex die 135 (refer to FIG. 16) connected tothe raw material supply pipes 133 a, 133 b via packings 134 a, 134 b, amouthpiece 136 (refer to FIG. 16) detachably fixable to a lower endportion of the complex die 135, etc. The raw material supply pipe 133 abranches at an intermediate portion thereof into a plurality of (four inthis embodiment) pipe members striding over the raw material supply pipe133 b. The lower end portions of the branches of the raw material supplypipe 133 a are arranged around that of the raw material supply pipe 133b. As shown in FIGS. 16A and 16B, the complex die 135 has a frame typepartition wall 139 in an inner region of an outer frame 138 so that theinterior of the complex die 135 is divided into two chambers 137 a, 137b, i.e., the complex die is formed so that the same kind of raw materialor two different kinds of raw materials supplied thereto via the rawmaterial supply pipes 133 a, 133 b are not mixed with each other. Evenwhen the raw material supplied through these supply pipes is the same,it is preferable to provide the partition wall 139 for the purpose ofregulating the extrusion rates separately. The particular parts of theinterior of the die of the extrusion molding machine 111 are formed byutilizing the corresponding parts of the first mode of embodiment.Although the raw material supply pipe 133 a is made to branch into fourmembers, the pipe may also be made to branch into a suitable number ofmembers, such as two members (refer to FIG. 17A), three members (referto FIG. 17B), etc.

A mouthpiece 136 has not smaller than two regions so that a raw materialis supplied thereto separately. Therefore, the regulation of theextrusion speed or extrusion rate of filaments is made very easily, andthe moldability of the raw material is improved remarkably. The detailsof a description of the mouthpiece will be given by quoting thecorresponding parts of the description of the first mode of embodiment.In this embodiment, a mouthpiece 171 (the area of the region thereofwhich is provided with holes H accounts for 90% of a total area of themouthpiece 171)(refer to FIG. 18A) having the holes at substantiallyregular intervals or at suitable intervals is used. In this mouthpiece171, an inner region 171 a and an outer region 171 b are defined by apartition wall 171 c shown by a broken line, and filaments of the sameor different materials are extruded separately and independently fromthese regions correspondingly to raw material supply pipes 133 a, 133 b.

A mouthpiece 172 (refer to FIG. 18B) may also be used, in which an innerregion 172 a and an outer region 172 b which are provided with amultiplicity of holes H are defined by a partition wall 172 c shown by abroken line. The inner region 172 a is formed in a deflected manner withrespect to the outer region 172 b so that the filaments corresponding tothe inner region 172 a are separated easily.

A mouthpiece 173 (refer to FIGS. 18C and 18D) may also be used. An innerregion 173 a and an outer region 173 b which are provided with amultiplicity of holes H are defined by a partition wall 173 c shown by abroken line. The inner region 173 a is held between the pair of outerregion 173 b. In order to form hollow portions in this mouthpiece,regions 173 d, 173 e which do not have holes H are provided in theportions thereof which correspond to the hollow portions, andcross-section square introduction members (pipes and the like) 173 f,173 g extending downward are provided on lower portions of the tworegions.

A mouthpiece 174 (refer to FIG. 19A) may be also used, in which an upperregion 174 a, a central region 174 b and a lower region 174 c which areprovided with a multiplicity of holes H are defined by partition walls174 d, 174 e shown by broken lines to form three stages (three layers)of regions.

A mouthpiece 175 (refer to FIG. 19B) may be also used, in which an upperregion 175 a and a lower region 175 b which are provided with amultiplicity of holes H are defined by a partition wall 175 c shown by abroken line to form two stages (two layers) of regions.

A mouthpiece 176 (refer to FIG. 19C) may be also used, in which a leftregion 176 a and a right region 176 b which are provided with amultiplicity of holes H are defined by a partition wall 176 c shown by abroken line to form two rows (two layers) of regions.

A mouthpiece 177 (refer to FIG. 19D) may be also used, in which a region177 a provided with a multiplicity of holes H, and a slit (linear hole)177 b formed in a suitable portion, such as a central portion, etc. soas to extend parallel to a predetermined direction (lengthwise directionin this example) are defined by partition walls 177 c shown by brokenlines. The slit 177 b exists in a region between the partition walls 177c shown by broken lines. The width, length or position of the slit(linear hole) 177 b can be suitably selected. When a raw material issupplied from the same die to the region 177 a having many holes H andslit (linear hole) 177 b, the wavy form of FIG. 3B is deformed, and themoldability of the material is deteriorated in some cases. However, whenthe above-mentioned mouthpiece 177 is used, the raw material is suppliedfrom not smaller than two kinds of extrusion molding machines 111separately and independently to the holes H of the region 177 a and slit177 b, so that a suitable wavy form is obtained. Instead of the slit 177b, holes H may be provided. In such a case, it is recommended that thedensity of the holes H be set high.

Besides these mouthpieces, mouthpieces of various other specificationscan be used in practice. The density of the holes H formed in theabove-described mouthpieces is preferably set to 1 to 5/cm².

The method of manufacturing a three-dimensional netted structure of thefirst mode of embodiment, etc. is utilized.

According to the three-dimensional netted structures 101 to 107 of thetenth to sixteenth modes of embodiment, a resin difficult to beseparated or a resin impossible to be separated is used to form thefirst region 101 a, while a resin possible to be separated is used toform the second region 101 b, this resin being separated during arecycling operation, so that the recycling operation can be carried outrepeatedly.

A three-dimensional netted structure divided into regions in accordancewith the properties of the thermoplastic resins can be manufactured, andthe recycling of the thermoplastic resins can be done smoothly. A simpleoperation, such as a region separating operation or some other similaroperation advantageously makes it possible to change the shape of thenetted structure afterward. Since a raw material is supplied to themouthpiece from a plurality of extruders separately and independently,the moldability of the material for the three-dimensional structure isimproved.

An apparatus 210 for manufacturing three-dimensional netted structure ofa third mode of embodiment aims at providing a method of and anapparatus for manufacturing a three-dimensional netted structure,capable of preventing the deformation, which causes inconveniences, ofthe endless belts, omitting a finishing operation on a later stage,improving the degree of straightness of the surfaces of a nettedstructure, meeting a demand for a netted structure of modified shapes,and manufacturing a netted structure of an improved durability.

The construction of the parts of the apparatus for manufacturing thethree-dimensional netted structure 210 which are different from thecorresponding parts of the apparatuses of other modes of embodiment willbe described by utilizing the description of the first mode ofembodiment, etc. The apparatus 210 is formed of an extrusion moldingmachine 211, a pair of rolls 212, 213 provided in horizontal positionsspaced from each other by a predetermined distance, a pair of rolls 214,215 (refer to FIG. 20 and FIG. 21) provided below and in alignment withthe two rolls 212, 213 horizontally so as to be spaced from each otherby a predetermined distance, a motor for driving the rolls 212 to 215, atransmission formed of chains and gears and adapted to change the movingspeed of the rolls 212 to 215, a water tank for partly submerging of thetwo rolls 212, 213 and completely submerging the two rolls 214, 215, acontrol unit, meters, etc. Referring to FIG. 20, a structure providedwith three rolls by removing one of the lower rolls may be employed.

The rolls 212, 213 may be formed of cross-section circular rolls 224(refer to FIG. 22A) as well as rolls of modified shapes. Variousmodified modes of rolls are conceivable which include, for example, aroll 225 (refer to FIG. 22B) having a cross-section saw-tooth outercircumference, a roll having continuously formed recesses andprojections, for example, a roll 226 (refer to FIG. 22C) having an outercircumferential surface similar to that of a gear in section, a roll 227(refer to FIG. 22D) having not smaller than one projection 227 a (forexample, a triangular or circular projection) on an outercircumferential surface thereof, a cross-section elliptic roll 228(refer to FIG. 22E), a cross-section triangular or a hand-made ormechanically molded rice-shaped roll 229 (refer to FIG. 22F), across-section polygonal roll, for example, a cross-section octagonalroll 230 (refer to FIG. 22G), etc.

As shown in FIG. 21, the rolls 212 to 215 are provided with drivingshafts 212 a to 215 a respectively. The driving shafts 212 a to 215 aare supported rotatably on the respective bearings, and driven in thedirections of arrows in FIG. 20 by a driving motor via the transmission.

According to the apparatus 210 described above for manufacturing athree-dimensional netted structure, it becomes possible to omit afinishing operation carried out in a later stage, heighten the degree ofstraightness of surfaces of a netted structure, meet a demand forobtaining netted structures of modified shapes and improve thedurability of a netted structure.

A three-dimensional netted structure 401 of a seventeenth mode ofembodiment is a netted structure in which sparse portions and denseportions are provided. This netted structure can be applied to, forexample, a wall material from which a gardening container is suspended,a deck on which a gardening container is placed, a blind, a screen, abamboo blind-like article, a fence, and a gardening cushioning materialapplied to a floral decoration and the like.

The sparse and dense portions of the three-dimensional netted structure401 are formed through an operation for regulating a transfer speed ofthe draw-down unit, for example, endless conveyors or rollers, bycontrolling the rotational speed of the motor. This method enables anetted structure having sparse and dense portions stabler than those ofa netted structure manufactured by regulating the liquid pressure of theextrusion molding machine to be obtained.

As shown in FIG. 23A, low-density portions 401 a and high-densityportions 401 b are formed in order and in repetition. In addition, asshown in FIG. 23B, hollow portions 406A, 406B are provided through anetted structure so as to extend in a predetermined direction. Amodified mode of this netted structure may be a gardening cushioningmaterial 402 having a plurality of small through holes 407 a to 407 dextending therethrough in the lengthwise direction as shown in FIG. 23D.The ranges of the density of the sparse portions 401 a and denseportions 401 b can be set suitably. The raw material of thethermoplastic resin, etc. will be described by utilizing the descriptionof those of the first mode of embodiment.

In order to make hollow portions in the netted structure, regions 477 a,477 b not provided with the holes H are formed in the correspondingparts of the mouthpiece 471 as shown in FIG. 24, and downwardlyextending cross-section square introduction members (plate members,pipes, etc.) 477 c, 477 d are provided (refer to FIG. 24B) on lowerportions of these regions. There is another example of the mouthpiecewhich is formed of a mouthpiece 481 (the area of the region thereofwhich is provided with the holes H accounts for 90% of a total area ofthe mouthpiece)(refer to FIG. 24C) in which a predetermined number ofholes H are formed at substantially regular intervals. In order to formhollow portions in the netted structure, this mouthpiece is providedwith regions 487 a to 487 d not provided with the holes H in thecorresponding parts thereof, and downwardly extending cross-sectionsquare introduction members (plate members, pipes, etc.) 488 a to 488 dare provided (refer to FIG. 24D) on lower portions of the mentionedregions. The density of the holes H formed in the mouthpiece ispreferably 1 to 5/cm². Besides these mouthpieces, mouthpieces of variousspecifications can be used in practice.

The three-dimensional netted structure 401 can be used as substitutesfor a wall member from which a gardening container is suspended, a wallmember for a floral decoration, a blind and a fence. For example, asshown in FIG. 25, piles 480 (posts may be used instead) are driven intothe ground and set up, and the resultant piles are thrust into thehollow portions 406A, 406B of the three-dimensional netted structure 401and fixed. The three-dimensional netted structure 401 may be dividedinto a plurality of parts, and dimensional selectivity thereof may besecured by combining the divided netted structures with each other. Asuitable number of hanging baskets 482 provided with hooks 481 are hungon the sparse portions 401 a. The hooks 481 are hung on sparse portions401 a more easily than on dense portions 401 b. This netted structurecan also be utilized as a deck. For example, a three-dimensional nettedstructure 490 is not provided with hollow portions but it ismanufactured in a step similar to the step of manufacturing thethree-dimensional netted structure 401, so that a culture pot 491, acontainer 492 and the like can be placed thereon. The netted structure490 can also be applied to a screen, a bamboo blind-like article, afence, a floral decoration, etc. As shown in FIG. 26, athree-dimensional netted structure 402 can be utilized as a roof, ascreen, and a partition for plants in a median strip of a road. Thenetted structure 402 is formed so that it can be fixed to a structure bya suitable device or by passing connecting members 403, such as strings,rings, pipes and the like through small holes 407 a to 407 c thereof.When this netted structure is utilized as a partition for the plants ina median strip of a road, a glare-proofing effect is displayed withrespect to the light of an automobile.

According to the three-dimensional netted structure 401 described above,it can be applied to a wall member for hanging baskets, a deck, a blind,etc. Moreover, this netted structure reduces the manufacturing cost, andhas a durability with respect to the wind and rain and sunlight. Thenetted structure is not rotted, and the flexure thereof does not occur.The netted structure is rarely discolored. This netted structure canemploy various colors, and the coloring of the netted structure can bedone freely, so that the range of the selection of colors expands.Moreover, the netted structure has a very high resiliency, and enables ablinding effect to increase and an outer appearance of different senseof quality to be provided, so that the netted structure is veryconvenient.

The three-dimensional netted structure can also be used as a seedbed forplanting a roof with trees. The netted structure is laid in a hole or arecess formed in a suitable position on a gas-permeable and awater-permeable tile. The culture earth is put in the hole or recess,and tree is planted therein.

The three-dimensional netted structure can also be used as a pavementmaterial by pasting gas-permeable and water-permeable tiles on an uppersurface thereof. Owing to the netted structure, the temperature can bereduced.

A three-dimensional netted structure can also be manufactured thecharacteristics of which reside in that the netted structure is formedby preparing as a raw material or a main raw material a thermoplasticresin containing a brittleness causing element, such as an inorganicsubstance, for example, talc; forming a plurality of helically andrandomly entangled and partly and thermally bonded filaments of the rawmaterial by extrusion molding; and cooling these filaments with aliquid, the brittle fracture of the product becoming able to be effectedby applying an external force thereto.

A three-dimensional netted structure obtained by preparing athermoplastic resin as a raw material or a main raw material; forming aplurality of helically and randomly entangled and partly and thermallybonded filaments of the raw material by extrusion molding; cooling thesefilaments with a liquid, and applying a fire resistant material to theresultant filaments or enclosing the filaments with a nonwoven carbonfiber, or a similar three-dimensional netted structure made of the samethermoplastic resin to which the fire resistant material is added canalso be manufactured. The three-dimensional netted structure enclosedwith a nonwoven cloth of carbon fiber can be provided in the ceiling andwalls.

A three-dimensional netted structure 510 of the fourth mode ofembodiment is manufactured by forming a three-dimensional nettedstructure 501 by using curved plates 582, 583 as shown in FIG. 27,instead of using the endless members and rolls. The curved plates 582,583 extend perpendicularly to the surface of the drawing, and are givenat their outer surfaces a slidability by coating the same withpolytetrafluoroethylene. The curved plates are rectangular in sideelevation. The curved plates 582, 583 are arranged so that a distancetherebetween decreases from upper portions thereof toward lower portionsthereof. The curved plates 582, 583 may have a fixed structure, or theymay be formed so that the density and shape thereof in the lateral andlongitudinal directions can be varied by rendering a distance of thecurved plates variable as shown by broken lines by reciprocating drivingunits 590, 591 (for example, fluid pressure cylinders). A curved plate584 is also provided below the curved plates 582, 583, and introducesthe netted structure 501 suitably to a downstream side draw-down unit.

INDUSTRIAL APPLICABILITY

According to the inventions described in claim 1 tob 19, a method of andan apparatus for manufacturing a three-dimensional netted structure,capable of omitting a finishing operation in a later stage, heighteningthe degree of straightness of side surfaces of the netted structure,meeting a demand for obtaining netted structure of modified shapes, andimproving the durability of the netted structure can be provided, andthe value of industrial utilization of these inventions in various kindsof industries is very large.

1. A three-dimensional netted structure comprising: a netted structurebeing manufactured by preparing a thermoplastic resin as a raw materialor a main raw material; and a sheet which is included in an internalportion of said netted structure, wherein said sheet is formed in a wavypattern and extends from one end to another end of said nettedstructure, wherein said resin is formed into a plurality of helicallyand randomly entangled, partly and thermally bonded filaments byextrusion molding, wherein said filaments are cooled with a liquid so asto obtain said netted structure which includes said sheet having apercentage of void of zero continuously in a material extrudingdirection, thereby forming said sheet into said wavy pattern in saidnetted structure in said material extruding direction, and wherein saidnetted structure is a three-dimensional plate type netted structurehaving an apparent density of 0.02 to 0.9 g/cm³.
 2. A method ofmanufacturing a three-dimensional netted structure, wherein said methodis applied to form said netted structure as defined in claim
 1. 3. Athree-dimensional netted structure comprising: a netted structure beingmanufactured by preparing a thermoplastic resin as a raw material or amain raw material, wherein said netted structure includes an innerregion having a predetermined apparent density and an outer peripheralregion adjacent said inner region having an apparent density higher thansaid predetermined apparent density, wherein said resin is formed into aplurality of helically and randomly entangled, partly and thermallybonded filaments by extrusion molding, wherein said filaments are cooledwith a liquid so as to obtain said netted structure having said innerregion and said outer peripheral region arranged continuously in amaterial extruding direction, and wherein said netted structure is athree-dimensional plate type netted structure having said predeterminedapparent density and said apparent density greater than saidpredetermined apparent density of 0.02 to 0.9 g/cm³.
 4. An apparatus formanufacturing a three-dimensional netted structure having a nettedstructure being obtained by extruding molten filaments of athermoplastic resin as a raw material or a main raw material,comprising: a die having a plurality of holes, said filaments beingdownward from said die; and drawing-down units partly-submerged inwater, having said filaments drop naturally in between, wherein saiddrawing-down units draw said filaments in between at a speed lower thana filament dropping speed, a distance between said drawing-down unitsbeing set smaller than a width of an assembly of said extrudedfilaments, wherein said drawing-down units are arranged so that foursurfaces of the assembly of said filaments contact said drawing-downunits before or after said drawing-down units being submerged, wherein acurved plate extends between said die and said draw-down unit therebyintroducing said filaments to said draw-down unit, and wherein saidcurved plate is given at their outer surfaces having a slidability, saidcurved plate is arranged so that a distance inbetween decreases fromupper portions thereof toward lower portions thereof.